Abstract:To explore the best pretreatment conditions for the digestion of Fe，Zn and Cu in tea.Microwave digestion technique was used to pretreat the samples.It was proposed to change the resolution of nitric acid content，temperature，digestion pressure and hold time by four research factors，and the L9（34）orthogonal table in the orthogonal design was used to optimize the pretreatment conditions in the tea pretreatment process.The recovery rate was used as the evaluation index.The content of Fe，Zn and Cu in tea was determined by flame atomic absorption spectrometry.The optimum pretreatment conditions for the element were sought.The order of the impact factors of microwave digestion of Fe were nitric acid content，digestion pressure，hold time and temperature.The best pretreatment conditions for microwave digestion were nitric acid 6 mL and temperature 190 ℃ and digestion pressure 50 bar，and hold time 20 min.As for Zn，the order of the impact factors was the hold time，followed by the temperature，then the nitric acid content，and finally the digestion pressure.The optimal digestion conditions were as follows：nitric acid content was 8 mL，and temperature was 190 ℃，and digestion pressure was 50 bar，hold time was 25 min.The order of factors affecting the microwave digestion effect of Cu in tea was temperature，holding time of pressure，HNO3 consume，and pressure.The best combination of sample pretreatment conditions found in this experiment was a HNO3 consume of 8 mL，a temperature of 170 ℃，a pressure of 60 bar，a holding time of pressure of 15 minutes.